Analysis of Individualized Silicone Rubber Bolus Using Fan Beam Computed Tomography in Postmastectomy Radiotherapy: A Dosimetric Evaluation and Skin Acute Radiation Dermatitis Survey.

Objective: To investigate the dosimetric effects of using individualized silicone rubber (SR) bolus on the target area and organs at risk (OARs) during postmastectomy radiotherapy (PMRT), as well as evaluate skin acute radiation dermatitis (ARD). Methods: A retrospective study was performed on 30 patients with breast cancer. Each patient was prepared with an individualized SR bolus of 3 mm thickness. Fan-beam computed tomography (FBCT) was performed at the first and second fractions, and then once a week for a total of 5 times. Dosimetric metrics such as homogeneity index (HI), conformity index (CI), skin dose (SD), and OARs including the heart, lungs, and spinal cord were compared between the original plan and the FBCTs. The acute side effects were recorded. Results: In targets' dosimetric metrics, there were no significant differences in Dmean and V105% between planning computed tomography (CT) and actual treatments (P > .05), while the differences in D95%, V95%, HI, and CI were statistically significant (P < .05). In OARs, there were no significant differences between the Dmean, V5, and V20 of the affected lung, V5 of the heart and Dmax of the spinal cord (P > .05) except the V30 of affected lung, which was slightly lower than the planning CT (P < .05). In SD, both Dmax and Dmean in actual treatments were increased than plan A, and the difference was statistically significant (P < .05), while the skin-V20 and skin-V30 has no difference. Among the 30 patients, only one patient had no skin ARD, and 5 patients developed ARD of grade 2, while the remaining 24 patients were grade 1. Conclusion: The OR bolus showed good anastomoses and high interfraction reproducibility with the chest wall, and did not cause deformation during irradiation. It ensured accurate dose delivery of the target and OARs during the treatment, which may increase SD by over 101%. In this study, no cases of grade 3 skin ARD were observed. However, the potential of using OR bolus to reduce grade 1 and 2 skin ARD warrants further investigation with a larger sample size.

The effect of implant shape and screw pitch on microdamage in mandibular bone.

PURPOSE: The aim of this study was to investigate the effect of implant shape and screw pitch on microdamage in bone during insertion of dental implants. MATERIALS AND METHODS: Thirty custom-made implants (length, 10 mm; diameters, 4.1 mm; cylindrical, tapered, and taper-cylindrical shapes; screw pitches, 1.25 and 0.8 mm; classified as 1.25C, 0.8C, 1.25T, 0.8T, 1.25TC, 0.8TC) were placed with a surgical device in the mandibles of eight goats. Two implant sites were prepared in the edentulous area on each side of the mandible. Implants were placed in a randomized order. Immediately after placement of the implants, the bone blocks with the implants were collected, bulk stained with basic fuchsin, embedded in methyl methacrylate, and sectioned. Histomorphometric quantification of the microcrack length (Cr.Le, µm); microcrack surface density (Cr.Le/B.Ar, µm/mm(2) ), and damaged bone area fraction (DB.Ar/B.Ar, %) were measured. RESULTS: The Cr.Le, Cr.Le/B.Ar, and DB.Ar/B.Ar values of 0.8TC group were 80.96 ± 17.55, 478.75 ± 51.85, and 4.40 ± 0.36, respectively. All these parameters of microdamage induced by 0.8TC were significantly lower than those induced by other five types of implants (p < .05). CONCLUSION: Taper-cylindrical implants with 0.8 mm screw pitch caused the least microdamage to the bone in comparison with the other five types of implants during placement of implants.

A comparative study of dog models for osteotome sinus floor elevation and dental implants in posterior maxilla subjacent to the maxillary sinus.

OBJECTIVE: The objective of this study was to investigate the suitability of beagles and Labrador retrievers as animal models for osteotome sinus floor elevation (OSFE) and dental implants in posterior maxilla subjacent to sinus. STUDY DESIGN: Ten beagles and 8 Labrador retrievers were included. Their posterior maxillas subjacent to the sinus were studied by a gross survey, CT scan, and histologic analysis. RESULTS: In the posterior maxilla subjacent to sinus, the bone height was significantly higher for Labrador retrievers than for beagles (P < .05). There was no significant difference in sinus size from the coronal section and its location from the sagittal section (P > .05) between Labrador retrievers and beagles. CONCLUSIONS: As an animal model, the Labrador is more suitable for OSFE and dental implants in posterior maxilla subjacent to sinus. The midpoint of the maxillary fourth premolar is an ideal site for implantation.